Fluid pump



May 10, 1966 T. H. osTER 3,250,477

FLUID PUMP Filed June 23, 1964 THOMAS l-'I @STER INVENTOR.

BY N

A 7' TURA/EVS United States Patent O 3,259,477 FLUID PUMP Thomas H. Oster, Dearborn, Mich., assigner to Ford Motor Company, Dearborn, Mich., a corporation of Delaware Filed .lune 23, 1964, Ser. No. 377,193 16 Claims. (Cl. 239-332) This invention relates to a fluid pump and more particularly to an injection pump for the fuel injection system of an internal combustion engine.

It has been proposed to employ a deformable elastomeric body as a pumping member in a fuel injection system in place of a more conventional reciprocating plunger. The elastomeric body defines one side of a pumping cavity and is deformed by a driving member to vary the volume within the pumping chamber and impelled fuel to the fuel injection nozzle. By employing an elastomeric body, the sealing problems attendant with the conventional plunger are substantially reduced. The cost of the injection pump also may be reduced since close tolerances are not required between the plunger and the bore in which it reciprocates.

Injection pumps employing elastomeric bodies are shown in the patents to Pierce 2,929,332 issued March 22, 1960I and Dolza et al. 2,913,991, issued November 24, 1959, both entitled Pump. In the devices shown in these patents, the driving member that contacts the elastomeric body has substantially the same cross-sectional area as the body at its Contact with the body. Since the amount of fuel injected during each cycle is very small, particularly at partial loads, a small degree of driving member movement is required to produce the necessary volume change within the pumping cavity. The small movements require close tolerances in the design of the pump driving member to avoid high magnitude errors in displaced volume.

It is therefore the principal object of this invention to provide a fluid pump embodying an elastomeric body and one that does not have high tolerance requirements.

A fluid pump embodying this invention comprises a casing having a cavity within. An elastomeric body received in the cavity forms a closure at one end thereof. A first surface of the elastomeric body and the enclosed portion of the cavity forms the pumping chamber. Fluid inlet and iiuid outlet means communicate with the pumping chamber for iiuid ow to and from the chamber. A driving member is positioned in engagement with a second surface of the elastomeric body for deforming the second surface by direct contact. The deformation of the second surface causes elastic deformation of the first surface for varying the volume of the pumping chamber and impelling fluid from the inlet to the outlet. The driving member has substantially less cross-sectional area at its contact with the second surface than the cross-sectional area of the second surface.

The pump described in the foregoing paragraph may be used as a fuel injection pump in an internal combustion engine injection system by connecting the fuel inlet with a source of fuel under pressure. The fuel outlet is connected by means of a discharge valve and conduit to a fuel injection nozzle. The driving member may be driven in timed speed with the engine crankshaft by any suitable manner.

Further objects and advantages of this invention will become more apparent when considered in conjunction with the accompanying drawing wherein the single ligure illustrates schematically a fuel injection system for an internal combustion engine embodying this invention.

Referring now in detail to the drawing, a fuel injection pump is indicated generally by the reference numeral 11. The injection pump 11 comprises a tubular casing 12 enclosed at its upper end by an upper end cap 13. A lower end cap 14 having a pilot portion 15 that is threaded in a cylindrical cavity 1'6 that extends longitudinally through the tubular casing 12. A shoulder 17 of the lower end cap 14 engages the lower end of the tubular casing 12.

An elastomeric body 1S formed of a resilient, substantially incompressible material has an external surface 19 that is complementary to the cylindrical cavity d6 is received in the upper end of the tubular casing 12. The external surface 19 is vulcanized or bonded in any suitable manner to the tubular casing 12 along the major portion of its length. The elastomeric body 18 may be formed.

from any suitable material that is impervious to fuel and is resilient and incompressible. A normally planar upper end surface 21 of the elastomeric body 18 opposes a planar lower surface 22 of the upper end cap 13. The surfaces 21 and 22 and the confined portion of the cylindrical cavity 16 form a pumping chamber 23.

A normally planar lower surface 24 of the elastomeric body 1S is engaged by a plate 25 that isaffixed to the tubular casing 12 within the cylindrical cavity 16. A cavity circular aperture 26 is formed at the center of plate 25. A bore 27 in the lower end cap 14 supports a pump driving member of plunger 28 for reciprocation. The bore 27 is axially aligned with the circular aperture 26 and with the cylindrical cavity 16 but is smaller in diameter. An upper surface 29 of the plunger 28 engages the lower surface 24 of the elastomeric body 18. The cross-sectional area of the plunger 28 is Substantially less at its point of contact than the cross-sectional area of the surface 24. v

A lower end 31 of the plunger 28 is engaged by a cam 32 supported upon a camshaft 33. The camshaft is driven in timed relation with the engine crankshaft in any suitable manner. Rotation of the cam 32 causes reciprocation of the plunger 28. As the plunger 28 reciprocates, the lower surface 24 of the elastomeric body 18 is deformed. The deformation is transmitted through the elastomeric body 18 because of its incompressibility to the upper surface 21 with a resulting variation in volume within the pumping chamber 23.

The variation in volume within the pumping chamber 23 is employed to impel fuel from a fuel source to a fuel injection nozzle, as will now be described. A fuel tank 34 is connected by a first inlet conduit 35 to the inlet side of a primary fuel pump 36. The outlet side of the primary fuel pump 36 is connected by a second inlet conduit 37 to an inlet fitting 38 received in the upper end cap 13. An inlet fuel passage 39 extends through the end cap 13 from the inlet fitting 38 to the pumping charnber 23. A check valve, indicated generally by the reference numeral 41, is positioned at the discharge end of the passage 39 to permit fuel to flow only into the chamber 23 through the passage 39.

An outlet passage 42 is also formed in the upper end plate 13. An outlet fitting 43 is threaded into the end plate 13 at the mouth of the outlet passage 42. Any suitable type of discharge valve, as indicated generally by the reference numeral 44, may be positioned in the discharge circuit of the injection pump 11. A discharge conduit 45 extends from the outlet iitting 43 to a fuel injection nozzle, indicated generally by the reference numeral 46.

It should be readily apparent that as the plunger 28 reciprocates, the pumping chamber 23 will alternately expand and contract in volume. During the expansion cycle which results from the resilience of elastomeric body 18, fuel under pressure from the primary fuel pump 36 will enter the pumping chamber 23 through the open check valve 41. The delivery valve 44 will be closed at this time. As the plunger 28 moves upwardly to compress the pumping chamber 23, the inlet check valve 41 will close and fuel will be impelled from the pumping chamber 23 past the discharge valve 43 to the injection nozzle 46.

Since the -cross-sectional area of the plunger 23 is substantially less than the cross-sectional area of the elastomeric body 18, a fairly sizeable stroke or length of reciprocation is required to yobtain the necessary change in volume in the pumping chamber 23. This permits a Wider tolerance in the finish of the cam 32. The shape of the lower end of the plunger 28 is immaterial so long as its cross-sectional area is small at the upper end throughout a length equal to the stroke.

Only a single injection pump has been illustrated and described. It is to be understood that oneinjection pump may be provided for each cylinder or injection nozzle of a multi-cylinder engine. The individual pumps may be arranged in line wherein a longitudinally spaced cam or a single wide cam will be employed as a drive member. ,The pumps also can be arranged in a radial form so that any number may be driven from a single cam. Various other changes and modifications may be made without departing from the spirit and scope of the invention, as defined by the appended claims.

What is claimed is:

1. A fluid pump comprising a casing having a cavity therein, a resilient incompressible body received in said cavity and forming a closure at one end thereof, a irst surface of said body and the enclosed portion of said 'cavity forming a pumping chamber, uid inlet and liuid outlet means in communication with said pumping chamher for fluid ow to and from said pumping chamber, and a driving member in engagement with a second surface of said body, said driving member being movable for yforming a closure at one end thereof, a first surface of said elastomeric body and the enclosed portion of said cavity forming a pumping chamber, uid inlet and fluid outlet means communicating with said pumping chamber, for fluid flow to and from said pumping chamber and a driving member in engagement with a second surface of said elastomeric body, said driving member being movable for alternately deforming said second surface, said first and second surfaces being axially spaced `for causing elastic deformation of said iirst surface upon deformation of said second surface to vary the volume of said pumping cavity and impel fluid from said fuel inlet to said fuel outlet, said driving member having substantially less cross-sectional area at its contact with said surface than the .cross-sectional area of said second surface.

3. A fluid pump comprising a casing having a cavity therein, a resilient incompressible body having an external surface in engagement with and bonded to said cavity along at least a portion of the length of said external surface, a first end surface of said body forming a closure at one end of said cavity to form a pumping chamber therewith, fluid inlet and fluid outlet means communicating with said pumping chamber for fluid flow to and from said pumping chamber, and a driving member in engagement with a second end surface of said body, said driving member being movable for alternately deforming said second end surface, the deformation of said second end surface causing deformation of said first end surface due to the incompressibility of said body for varying thevolume of said pumping chamber and the impelling iiuid from said fluid inlet to said fluid outlet.

4. A fluid pump comprising a casing having a cavity therein, an elastomeric body received in said cavity and forming a closure at one end thereof, a irst surface of said elastomeric body and the enclosed portion of said cavity forming a pumping chamber, iiuid inlet and fluid outlet means communicating with said pumping chamber for liuid liow to and from said pumping chamber, and a driving member supported for reciprocation, one end-of said driving member being in engagement with a second surface of said elastomeric body for deforming said second surface upon reciprocation, the deformation of said second surface causing elastic deformation of said first surface for varying the Volume of said pumping cavity and impelling fluid from said iiuid inlet means to said iiuid outlet means, said one end of said driving member having substantially less cross-sectional area than crosssectional area of said second surface.

5. A fluid pump comprising a casin-g having a cavity therein, a resilient incompressible body received in said cavity and forming a closure at one end thereof, a irst surface of said body and the enclosed portion of said cavity forming a pumping chamber, fluid inlet and fluid outlet means communicating with said pumping chamber for iiuid diow to and from said pumping chamber, and a driving member supported for reciprocation, one end of said driving member being in en-gagement with a second surface of said body for deforming said second surface upon reciprocation, the deformation of said second surface causing deformation of said first surf-ace due to the incompressibi'lity of said body for varying the volume of said pumping cavity and impelling fluid from said inlet means to said fluid outlet means, said one end of said driving member having a cross-sectional area throughout a length equal to the stroke of said drivin-g member that is substantially less than the cross-sectional area of said second surface.

`6. A uid pump comprising a casing having a cavity therein, an elastomeric body having an external surface in engagement with said cavity and bonded thereto along at least a portion of its length, `a first end surface of said elastomeric body closing said cavity and forming a pumping chamber therewith, iiuid inlet and fluid outlet means in communication with said pumping chamber for fluid flow to and from said pumping chamber, and a driving member supported for reciprocation, said driving member having an end portion in engagement with the second end surface of said elastomeric body, said end portion of said driving member being adapted to deform said second end surface upon reciprocation of said driving member, the deformation of said second end surface causing elastic `deformation of said first end surface for varying lthe volume of said pumping chamber and impelling fluid from said fluid inlet means to said fluid outlet means, said end portion of said driving member having a crosssectional area throughout a length equal to the stroke of said driving member that is substantially less than the cross-sectional area of said second end surface.

7. A fuel injection system for an internal combustion engine comprising a fuel injection nozzle, an injection pump comprising a casing having a cavity therein, an elastomeric body received in said cavity and forming a closure at one end thereof, a yfirst surface of said elas- `tomeric body and Ithe enclosed portion of said cavity forming a pumping chamber, a source of fuel, a fuel inlet conduit extending from said source of fuel to said pumping chamber, a fuel outlet conduit including a delivery valve extending from said pumping chamber to said injection nozzle, and `a driving member in engagement with a second surface of said elastomeric body, said driving member being movable for alternately deforming said second surface, the deformation `of said second surface causing elastic deformation of said yfirst surface for varying the volume of said pumping chamber and impelling fuel from said pumping chamber to said fuel injection nozzle through said fuel outlet conduit, said driving member having substantially less cross-section-al area at its contact with said second surface than the cross-sectional area of said second surface.

8. A fuel injection system for an internal combustion engine comprising a fuel injection nozzle, an injection pump comprising a casing having a cavity therein, an elastomeric body havin-g an external surface in engagement with said cavity and bonded thereto, a first end surface of said elastomeric body forming a closure for said cavity to form a pumping ch-amber therewith, a source of fuel, fuel inlet lmeans including a primary fuel pump interconnecting said source of fuel with said pumping chamber, fuel outlet means including a delivery valve interconnecting said pumping chamber with said fuel injection nozzle, yand a Idriving member in enga-gement with a second end surface of said elastomeric body, said driving member being movable for alternately deforming said second end surface, the deformation of said second end surface causing elastic deformation of said first end surface for varying the volume of said pumping chamber and impelling fuel from said pumping chamber to said fuel injection nozzle.

9. A fuel injection system for an internal combustion engine comprising a fuel injection nozzle, an injection pump comprising a casing having a cavity therein, an elastomeric body received in said cavity and forming a closure at one end thereof, a first surface of said elastomeric body and the enclosed portion of said cavity forming a pumping chamber, a source of fuel, fuel inlet means including a primary fuel pump interconnecting said source of fuel with said pumping chamber, fuel outlet means including a delivery valve interconnect-ing said pumping chamber with said fuel injection nozzle, and a driving member supported for reciprocation, said driving member having an end thereof in engagement with a second surface of said elastomeric body for deforming said second surface upon reciprocation of said driving member, the deformation of said second surface causing elastic deformation of said first surface for varying the volume of said pumping chamber and impelling fuel from said pumping chamber to said fuel injection nozzle, said end of said driving -member having a cross-sectional area throughout a len-gth equal to the stroke of said driving member that is substantially less than the cross-sectional area of said second surface.

10. A fuel injection system for an internal combustion engine comprising a fuel injection nozzle, yan injection pump comprising a casing having a cavity therein, an elastomeric body having an externa-l surface in engagement with and bonded to said cavity, a first end surf-ace of said elastomeric body forming a closure for said cavity and forming a pumping chamber therein, a source of fuel, a primary fuel pump, inlet conduit means interconnecting said source of fuel with said primary fuel pump and said primary lfuel pump with said pumping chamber, a fuel outlet conduit including a delivery valve interconnecting said pumping chamber with said fuel injection nozzle, a driving member supported for reciprocation, said driving member having an end surface in engagement with a second end surface of said elastomeric body for deforming said second end surface upon reciprocation of said driving member, the deformation of said second end surface causing elastic Adeformation of said first end surface for varying the volume of said pumping chamber and impelling fuel from said pumping chamber to said fuel injection nozzle, said end of said driving member having a cross-sectional area throughout a length equal to the stroke of said driving member that is substantially less than the cross-sectional area of said second end surface.

References Cited by the Examiner UNITED STATES PATENTS 2,929,332 `3/1960 Pierce 10S- 148 2,974,599 3/1961 DOlZa 103-148 X 3,127,845 4/1964 Voelcker 103-148 MARK NEWMAN, Primary Examiner.

W. E. CGLEMAN, Assistant Examiner. 

7. A FUEL INJECTION SYSTEM FOR AN INTERNAL COMBUSTION ENGINE COMPRISING A FUEL INJECTION NOZZLE, AN INJECTION PUMP COMPRISING A CASING HAVING A CAVITY THEREIN, AN ELECTROMERIC BODY RECEIVED IN SAID CAVITY AND FORMING A CLOSURE AT ONE END THEREOF, A FIRST SURFACE OF SAID ELASTOMERIC BODY AND THE ENCLOSED PORTION OF SAID CAVITY FORMING A PUMPING CHAMBER, A SOURCE OF FUEL, A FUEL INLET CONDUIT EXTENDING FROM SAID SOURCE OF FUEL TO SAID PUMPING CHAMBER, A FUEL OUTLET CONDUIT INCLUDING A DELIVERY VALVE EXTENDING FROM SAID PUMPING CHAMBER TO SAID INJECTION NOZZLE, AND A DRIVING MEMBER IN ENGAGEMENT WITH A SECOND SURFACE OF SAID ELECTROMERIC BODY, SAID DRIVING MEMBER BEING MOVABLE FOR ALTERNATELY DEFORMING SAID SECOND SURFACE, THE DEFORMATION OF SAID SECOD SURFACE CAUSING ELASTIC DEFORMATION OF SAID FIRST SURFACE FOR VARYING THE VOLUME OF SAID PUMPING CHAMBER AND IMPELLING FUEL FROM SAID PUMPING CHAMBER TO SAID FUEL INJECTION NOZZLE THROUGH SAID FUEL OUTLET CONDUIT, SAID DRIVING MEMBER HAVING SUBSTANTIALLY LESS CROSS-SECTIONAL AREAAT ITS CONTACT WITH A SAID SECOND SURFACE THAN THE CROSS -SECTIONAL AREA OF SAID SECOND SURFACE. 